SHM Converge Scientific Abstract ePoster Gallery-Fentanyl-Induced Serotonin Syndrome: A Case of Opioid-Associated Serotonergic Toxicity

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This case report describes a 36-year-old man with opioid use disorder who developed neuropsychiatric symptoms and rhabdomyolysis after an opioid overdose complicated by seizure. On presentation, he had hypertension, tachycardia, tongue fasciculations, mild bilateral resting tremor, inducible clonus, slowed speech, and later developed fever and confusion. He remained adequately oxygenated and was initially afebrile.<br /><br />The team diagnosed serotonin syndrome using Hunter’s criteria, based on exposure to fentanyl and the presence of tremor and inducible clonus. His symptoms improved after treatment with a benzodiazepine taper, cyproheptadine, aggressive hydration, and electrolyte repletion.<br /><br />The report emphasizes that serotonin syndrome is usually associated with combinations such as SSRIs or SNRIs with MAO inhibitors, but certain analgesics can also trigger it. Meperidine and tramadol inhibit serotonin reuptake, while fentanyl is thought to directly activate serotonin receptors, increasing serotonergic activity. In this patient, transition from fentanyl to buprenorphine/naloxone may have contributed to additive serotonergic effects.<br /><br />A key message is that post-fentanyl neurotoxicity is not always due to overdose or withdrawal. In patients with polysubstance use, serotonin syndrome can be mistaken for opioid withdrawal, so clinicians should maintain a high index of suspicion when autonomic or neuropsychiatric symptoms occur after opioid changes. Prompt recognition and discontinuation of serotonergic agents are essential for recovery.

Asset Subtitle

Riddhi Patel

Meta Tag

Author List Angelica Rozenfeld, Dayita Wable, Hanna Cholerzynska, Neil E. Chen, Riddhi Patel, Thomas F. Fusillo

Category Clinical Vignettes

Concept Serotonin Syndrome

Concept Hunter Criteria

Concept Stopping Serotonergic Agents

Concept Opioid Exposure

Concept Clonus

Distinguished Non-Finalist

Presenter Organization Mount Sinai Morningside/West

Presenting Author Riddhi Patel

Track Adult

Keywords

serotonin syndrome

fentanyl

opioid overdose

rhabdomyolysis

Hunter criteria

buprenorphine/naloxone

opioid use disorder

neuropsychiatric symptoms

cyproheptadine

opioid withdrawal

Serotonin Syndrome

Hunter Criteria

Stopping Serotonergic Agents

Opioid Exposure

Clonus